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Lee JY, Kim HY, Martorano P, Riad A, Taylor M, Luedtke RR, Mach RH. In vitro characterization of [ 125I]HY-3-24, a selective ligand for the dopamine D3 receptor. Front Neurosci 2024; 18:1380009. [PMID: 38655111 PMCID: PMC11036874 DOI: 10.3389/fnins.2024.1380009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Accepted: 03/14/2024] [Indexed: 04/26/2024] Open
Abstract
Introduction Dopamine D3 receptor (D3R) ligands have been studied for the possible treatment of neurological and neuropsychiatric disorders. However, selective D3R radioligands for in vitro binding studies have been challenging to identify due to the high structural similarity between the D2R and D3R. In a prior study, we reported a new conformationally-flexible benzamide scaffold having a high affinity for D3R and excellent selectivity vs. D2R. In the current study, we characterized the in vitro binding properties of a new radioiodinated ligand, [125I]HY-3-24. Methods In vitro binding studies were conducted in cell lines expressing D3 receptors, rat striatal homogenates, and rat and non-human primate (NHP) brain tissues to measure regional brain distribution of this radioligand. Results HY-3-24 showed high potency at D3R (Ki = 0.67 ± 0.11 nM, IC50 = 1.5 ± 0.58 nM) compared to other D2-like dopamine receptor subtypes (D2R Ki = 86.7 ± 11.9 nM and D4R Ki > 1,000). The Kd (0.34 ± 0.22 nM) and Bmax (38.91 ± 2.39 fmol/mg) values of [125I]HY-3-24 were determined. In vitro binding studies in rat striatal homogenates using selective D2R and D3R antagonists confirmed the D3R selectivity of [125I]HY-3-24. Autoradiography results demonstrated that [125I]HY-3-24 specifically binds to D3Rs in the nucleus accumbens, islands of Calleja, and caudate putamen in rat and NHP brain sections. Conclusion These results suggest that [125I]HY-3-24 appears to be a novel radioligand that exhibits high affinity binding at D3R, with low binding to other D2-like dopamine receptors. It is anticipated that [125I]HY-3-24 can be used as the specific D3R radioligand.
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Affiliation(s)
- Ji Youn Lee
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Ho Young Kim
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Paul Martorano
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Aladdin Riad
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Michelle Taylor
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX, United States
| | - Robert R. Luedtke
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX, United States
| | - Robert H. Mach
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
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Tian GL, Hsieh CJ, Taylor M, Lee JY, Luedtke RR, Mach RH. Design and Synthesis of D 3R Bitopic Ligands with Flexible Secondary Binding Fragments: Radioligand Binding and Computational Chemistry Studies. Molecules 2023; 29:123. [PMID: 38202706 PMCID: PMC10779535 DOI: 10.3390/molecules29010123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Revised: 12/20/2023] [Accepted: 12/21/2023] [Indexed: 01/12/2024] Open
Abstract
A series of bitopic ligands based on Fallypride with a flexible secondary binding fragment (SBF) were prepared with the goal of preparing a D3R-selective compound. The effect of the flexible linker ((R,S)-trans-2a-d), SBFs ((R,S)-trans-2h-j), and the chirality of orthosteric binding fragments (OBFs) ((S,R)-trans-d, (S,R)-trans-i, (S,S)-trans-d, (S,S)-trans-i, (R,R)-trans-d, and (R,R)-trans-i) were evaluated in in vitro binding assays. Computational chemistry studies revealed that the interaction of the fragment binding to the SBF increased the distance between the pyrrolidine nitrogen and ASP1103.32 of the D3R, thereby reducing the D3R affinity to a suboptimal level.
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Affiliation(s)
- Gui-Long Tian
- Division of Nuclear Medicine and Clinical Molecular Imaging, Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; (G.-L.T.); (C.-J.H.)
| | - Chia-Ju Hsieh
- Division of Nuclear Medicine and Clinical Molecular Imaging, Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; (G.-L.T.); (C.-J.H.)
| | - Michelle Taylor
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX 76107, USA; (M.T.)
| | - Ji Youn Lee
- Division of Nuclear Medicine and Clinical Molecular Imaging, Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; (G.-L.T.); (C.-J.H.)
| | - Robert R. Luedtke
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX 76107, USA; (M.T.)
| | - Robert H. Mach
- Division of Nuclear Medicine and Clinical Molecular Imaging, Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; (G.-L.T.); (C.-J.H.)
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Tian GL, Hsieh CJ, Taylor M, Lee JY, Riad AA, Luedtke RR, Mach RH. Synthesis of bitopic ligands based on fallypride and evaluation of their affinity and selectivity towards dopamine D 2 and D 3 receptors. Eur J Med Chem 2023; 261:115751. [PMID: 37688938 PMCID: PMC10841072 DOI: 10.1016/j.ejmech.2023.115751] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 08/08/2023] [Accepted: 08/21/2023] [Indexed: 09/11/2023]
Abstract
The difference in the secondary binding site (SBS) between the dopamine 2 receptor (D2R) and dopamine 3 receptor (D3R) has been used in the design of compounds displaying selectivity for the D3R versus D2R. In the current study, a series of bitopic ligands based on Fallypride were prepared with various secondary binding fragments (SBFs) as a means of improving the selectivity of this benzamide analog for D3R versus D2R. We observed that compounds having a small alkyl group with a heteroatom led to an improvement in D3R versus D2R selectivity. Increasing the steric bulk in the SBF increase the distance between the pyrrolidine N and Asp110, thereby reducing D3R affinity. The best-in-series compound was (2S,4R)-trans-27 which had a modest selectivity for D3R versus D2R and a high potency in the β-arrestin competition assay which provides a measure of the ability of the compound to compete with endogenous dopamine for binding to the D3R. The results of this study identified factors one should consider when designing bitopic ligands based on Fallypride displaying an improved affinity for D3R versus D2R.
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Affiliation(s)
- Gui-Long Tian
- Division of Nuclear Medicine and Clinical Molecular Imaging, Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Chia-Ju Hsieh
- Division of Nuclear Medicine and Clinical Molecular Imaging, Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Michelle Taylor
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center-Fort Worth, Texas, TX, 76107, USA
| | - Ji Youn Lee
- Division of Nuclear Medicine and Clinical Molecular Imaging, Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Aladdin A Riad
- Division of Nuclear Medicine and Clinical Molecular Imaging, Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Robert R Luedtke
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center-Fort Worth, Texas, TX, 76107, USA
| | - Robert H Mach
- Division of Nuclear Medicine and Clinical Molecular Imaging, Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA.
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Hsieh CJ, Giannakoulias S, Petersson EJ, Mach RH. Computational Chemistry for the Identification of Lead Compounds for Radiotracer Development. Pharmaceuticals (Basel) 2023; 16:317. [PMID: 37259459 PMCID: PMC9964981 DOI: 10.3390/ph16020317] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Revised: 02/15/2023] [Accepted: 02/16/2023] [Indexed: 11/19/2023] Open
Abstract
The use of computer-aided drug design (CADD) for the identification of lead compounds in radiotracer development is steadily increasing. Traditional CADD methods, such as structure-based and ligand-based virtual screening and optimization, have been successfully utilized in many drug discovery programs and are highlighted throughout this review. First, we discuss the use of virtual screening for hit identification at the beginning of drug discovery programs. This is followed by an analysis of how the hits derived from virtual screening can be filtered and culled to highly probable candidates to test in in vitro assays. We then illustrate how CADD can be used to optimize the potency of experimentally validated hit compounds from virtual screening for use in positron emission tomography (PET). Finally, we conclude with a survey of the newest techniques in CADD employing machine learning (ML).
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Affiliation(s)
- Chia-Ju Hsieh
- Division of Nuclear Medicine and Clinical Molecular Imaging, Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Sam Giannakoulias
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - E. James Petersson
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Robert H. Mach
- Division of Nuclear Medicine and Clinical Molecular Imaging, Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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Kim HY, Lee JY, Hsieh CJ, Taylor M, Luedtke RR, Mach RH. Design and Synthesis of Conformationally Flexible Scaffold as Bitopic Ligands for Potent D 3-Selective Antagonists. Int J Mol Sci 2022; 24:ijms24010432. [PMID: 36613875 PMCID: PMC9820167 DOI: 10.3390/ijms24010432] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 12/22/2022] [Accepted: 12/24/2022] [Indexed: 12/28/2022] Open
Abstract
Previous studies have confirmed that the binding of D3 receptor antagonists is competitively inhibited by endogenous dopamine despite excellent binding affinity for D3 receptors. This result urges the development of an alternative scaffold that is capable of competing with dopamine for binding to the D3 receptor. Herein, an SAR study was conducted on metoclopramide that incorporated a flexible scaffold for interaction with the secondary binding site of the D3 receptor. The alteration of benzamide substituents and secondary binding fragments with aryl carboxamides resulted in excellent D3 receptor affinities (Ki = 0.8-13.2 nM) with subtype selectivity to the D2 receptor ranging from 22- to 180-fold. The β-arrestin recruitment assay revealed that 21c with 4-(pyridine-4-yl)benzamide can compete well against dopamine with the highest potency (IC50 = 1.3 nM). Computational studies demonstrated that the high potency of 21c and its analogs was the result of interactions with the secondary binding site of the D3 receptor. These compounds also displayed minimal effects for other GPCRs except moderate affinity for 5-HT3 receptors and TSPO. The results of this study revealed that a new class of selective D3 receptor antagonists should be useful in behavioral pharmacology studies and as lead compounds for PET radiotracer development.
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Affiliation(s)
- Ho Young Kim
- Vagelos Laboratories, Department of Radiology, University of Pennsylvania, 1012, 231 S. 34th Street, Philadelphia, PA 19104, USA
| | - Ji Youn Lee
- Vagelos Laboratories, Department of Radiology, University of Pennsylvania, 1012, 231 S. 34th Street, Philadelphia, PA 19104, USA
| | - Chia-Ju Hsieh
- Vagelos Laboratories, Department of Radiology, University of Pennsylvania, 1012, 231 S. 34th Street, Philadelphia, PA 19104, USA
| | - Michelle Taylor
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
| | - Robert R. Luedtke
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
| | - Robert H. Mach
- Vagelos Laboratories, Department of Radiology, University of Pennsylvania, 1012, 231 S. 34th Street, Philadelphia, PA 19104, USA
- Correspondence:
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Kiss B, Krámos B, Laszlovszky I. Potential Mechanisms for Why Not All Antipsychotics Are Able to Occupy Dopamine D 3 Receptors in the Brain in vivo. Front Psychiatry 2022; 13:785592. [PMID: 35401257 PMCID: PMC8987915 DOI: 10.3389/fpsyt.2022.785592] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Accepted: 02/25/2022] [Indexed: 11/29/2022] Open
Abstract
Dysfunctions of the dopaminergic system are believed to play a major role in the core symptoms of schizophrenia such as positive, negative, and cognitive symptoms. The first line of treatment of schizophrenia are antipsychotics, a class of medications that targets several neurotransmitter receptors in the brain, including dopaminergic, serotonergic, adrenergic and/or muscarinic receptors, depending on the given agent. Although the currently used antipsychotics display in vitro activity at several receptors, majority of them share the common property of having high/moderate in vitro affinity for dopamine D2 receptors (D2Rs) and D3 receptors (D3Rs). In terms of mode of action, these antipsychotics are either antagonist or partial agonist at the above-mentioned receptors. Although D2Rs and D3Rs possess high degree of homology in their molecular structure, have common signaling pathways and similar in vitro pharmacology, they have different in vivo pharmacology and therefore behavioral roles. The aim of this review, with summarizing preclinical and clinical evidence is to demonstrate that while currently used antipsychotics display substantial in vitro affinity for both D3Rs and D2Rs, only very few can significantly occupy D3Rs in vivo. The relative importance of the level of endogenous extracellular dopamine in the brain and the degree of in vitro D3Rs receptor affinity and selectivity as determinant factors for in vivo D3Rs occupancy by antipsychotics, are also discussed.
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Affiliation(s)
- Béla Kiss
- Pharmacological and Drug Safety Research, Gedeon Richter Plc., Budapest, Hungary
| | - Balázs Krámos
- Spectroscopic Research Department, Gedeon Richter Plc., Budapest, Hungary
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Dopamine D3 Receptor: Contemporary Views of Its Function and Pharmacology for Neuropsychiatric Diseases. Biomolecules 2021; 11:biom11050713. [PMID: 34064602 PMCID: PMC8151522 DOI: 10.3390/biom11050713] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2021] [Accepted: 05/08/2021] [Indexed: 12/02/2022] Open
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